Commonly known as fungus gnats, plant gnats are small, nonbiting flies that thrive in decaying organic matter, such as mulch, compost and glass clippings. Plant gnats are also attracted to moist potting soil. Although these insects are generally harmless to plants, they can feed on plant roots and make plants vulnerable to root rot. Control of plant gnats becomes necessary when they heavily infest or damage plants. Since chemical treatment of plant gnats is unnecessary, get rid of plant gnats using natural control methods.
Things You'll Need
2 tsp. Bacillus thuringiensis subspecies Israelensis
Allow moist potting soil around potted plants to thoroughly dry. Since plant gnats require moist soil to reproduce, dry soil destroys their habitat. Eliminate all nearby moisture sources, such as damp mulch and grass clippings.
Remove any decomposing material from the gnat-infested area. Eliminate piles of decomposing compost, grass clippings and mulch to force plant gnats to flee.
Inspect the infested area after a week for lingering plant gnats. If the gnats persist, mix 2 tsp. of Bacillus thuringiensis subspecies Israelensis with 1 gallon of water in a garden sprayer. Bacillus thuringiensis subspecies Israelensis is a natural bacterium that kills plant gnats.
Spray the diluted bacterial solution onto the gnat-infested areas. Apply Bacillus thuringiensis subspecies Israelensis according to manufacturer's directions.
Purchase Bacillus thuringiensis subspecies Israelensis at a local nursery.
Catch plant gnats using yellow sticky traps.
- Oregon State University Extension Service; Do Your Potted Plants Have Fungus Gnats?; Carol Savonen
- North Carolina Cooperative Extension; Fungus Gnats Indoors; Michael Waldvogel; May 2004
- University of California Integrated Pest Management; Fungus Gnats, Shore Flies, Moth Flies, and March Flies; S. H. Dreistadt; August 2001